Large rivers have been selected as one of the satellite topics both within WP3 and WP4, because of their particular features which could not be analysed in the case study catchments framework. Large rivers are considered rivers with a catchment larger than 10,000 km2 and > 100 m3/s. This encompasses rivers such as the Danube, Rhine, Rhône, Ebro, Vistula but also major tributaries such as the Sava, Narew, and Main rivers. Most fulfil major socio-economic functions, which will remain strongly modified and thus direct the options for rehabilitation. Because of their multifunctional use, large rivers can often only be partially rehabilitated or mitigated to achieve Good Ecological Potential according to the Water Framework Directive. This report addresses both hydrological modifications and restoration (rehabilitation, mitigation) following a DPSIR approach for six case studies that are spread across Europe

The aim of this deliverable is to address the impact of hydromorphological degradation on floodplain and riparian ecosystems, with specific focus on vegetation, fish and invertebrate responses and to provide guidance on how to identify those impacts.

An introductory chapter summarises the research context and reviews the lessons for managers and stakeholders. Based on the results of the analyses, and the river styles typology developed in Work Package 2 of REFORM, a generic process is recommended for assessing the impact on floodplain and riparian ecosystems, incorporating our key findings. It also highlights the usefulness and limitations of existing EU Directives in providing a suitable legislative framework.

Assessments of instream impacts on riverine ecosystems make use of multi-site datasets, riparian and floodplain ecosystems are not subject to this type of extensive monitoring; hence, the results presented here are based primarily on case studies from across Europe.